Answer: 
Explanation: <u>Heats</u> <u>of</u> <u>formation</u> is the amount of heat necessary to create 1 mol of a compound from its molecular constituents. The basic conditions the substance is formed is at standard conditions: 1 atm and 25°C. Each compound has its own heat of formation per mol of compound (kJ/mol), but to an element is assigned a value of zero.
<u>Standard</u> <u>Enthalpy</u> <u>Change</u> is defined as the heat absorbed or released when a reaction takes place. It can be positive or negative, which means reaction is endothermic or exothermic, respectively.
Enthalpy change is calculated as the difference between the sum of heat formation of products and the sum of heat formation of the reactants:
For the reaction
2NH₃ + 3N₂O → 4N₂ + 3H₂O
2(-46.2) + 3(82.05) 4(0) + 3(-241.8)
![\Delta H^{0}=3(-241.8)-[ 2(-46.2)+3(82.05)]](https://tex.z-dn.net/?f=%5CDelta%20H%5E%7B0%7D%3D3%28-241.8%29-%5B%202%28-46.2%29%2B3%2882.05%29%5D)
<u>The standard enthalpy change for the reaction is </u><u> kJ</u>
Carbon can form a wide variety of organic compounds because:
Each carbon atom covalently bonds with toms of carbon, hydrogen oxygen, and nitrogen
A carbon atom can have 4 single valence electrons around it. This allows it to form covalent bonds with many different atoms.
Answer:
The statement is considered to be true
Explanation:
The statement is true because when elements chemically combine, there are interactions between their valence electrons, causing the two elements to be bonded together to form what is known as a compound.
Compounds can only be formed from interactions between two or more elements. examples include:
Hydrogen + Oxygen = H2O (water)
Sodium + Chlorine = NaCl
Note that if atoms of the same element combine, what is formed is a molecule, not a compound. Some atoms usually do this to attain stability. examples include = O2 H2 and N2. They are oxygen molecule, hydrogen molecule, and nitrogen molecule respectively.
Compounds are only formed when different elements combine to attain electronic stability.
Answer:
It increases when a catalyst is added.
Explanation:
The following factors control reaction rates:
1. Nature of reactants
2. Concentration of the reactants or pressure of gaseous
3. Temperature
4. Presence of catalyst
5. Sunlight
The addition of a foreign body to a reaction may influence the speed of the reaction. If a foreign body increases the rate of reaction, it is a called a positive catalyst or simply a catalyst. A negative catalyst is called an inhibitor.
A catalyst is a substance that is introduced into a chemical reaction to change the rate of the reaction without itself being affected at the end of the reaction.
Catalysts helps to reduce reaction time of many slow reactions. Most catalysts are specific in their actions and works on certain reactions or substrates.
Temperature change has a considerable effect on reaction rates since temperature is directly proportional to the average kinetic energy of reacting particles. Generally, reaction rate varies as temperature directly.
Answer:
The second student is right.
Explanation:
The coyote feed on not only phalaropes but many other organisms present in the environment for its survival. There are many other organisms present in the ecosystem such as mice, squirrel, cactus fruit etc. The coyote feeds on phalaropes, the phalaropes feeds on brine shrimp and the brine shrimp feeds on algae for its survival so in this way the ecosystem moves in the forward direction. The coyote feeds on phalaropes so the energy that is present in phalaropes transferred into coyote which only 10 % while the remaining is released in the atmosphere in the form of heat energy.
